It is important for pilots to know the layout of the taxiways and runways when taxing for takeoff or from landing. Navigation of an airport surface (taxiways/runways) can be as difficult (from a pilot's workload perspective) and dangerous (from an aviation safety perspective) as the airborne portion of the flight, especially in limited visibility of night and/or weather, or at unfamiliar airports. An increase in pilot workload typically results in decreased safety: the pilot must interpret the information provided on the screen occupying his thought processes when he may have many other decisions to make. Undesired results include taxing onto unapproved taxiways/runways and becoming disorientated while taxing.
Many vehicles, such as aircraft, are commonly equipped with one or more vision enhancing systems to convey flight path and/or flight management information. Such vision enhancing systems are designed and configured to assist a pilot when flying in conditions that diminish the pilot's view from the cockpit, such as, but not limited to, darkness and weather phenomenon. One example of a vision enhancing system is known as a synthetic vision system (hereinafter, “SVS”) and may be more generally described as a being a dynamic condition subsystem of the aircraft. An example of a synthetic vision system is disclosed in U.S. Pat. No. 7,352,292. Additionally, an exemplary synthetic vision system is available for sale in the market place under product name SmartView, manufactured by Honeywell International, Inc.
A typical SVS is configured to work in conjunction with a position determining unit associated with the aircraft as well as with dynamic sensors that sense the aircraft's altitude, heading, and attitude. The SVS typically includes a database containing information relating to the topography along the aircraft's flight path. The SVS receives inputs from the position determining unit indicative of the aircraft's location and also receives inputs from the dynamic sensors on board the aircraft indicative of the aircraft's heading, altitude, and attitude. The SVS is configured to utilize the position, heading, altitude, and orientation information and the topographical information contained in its database, and generate a three-dimensional image that shows the topographical environment through which the aircraft is flying from the perspective of a person sitting in the cockpit of the aircraft. The three-dimensional image may be displayed to the pilot on any suitable display unit accessible to the pilot. Using an SVS, the pilot can look at the display screen to gain an understanding of the three-dimensional topographical environment through which the aircraft is flying and can also see what lies ahead. One advantage of the SVS is that its image is clean and is not obstructed by any weather phenomenon. SV image integrity, however, is limited by the integrity of the information pre-stored in the database. Accordingly, incomplete and/or outdated database information can result in SV images of limited value.
Another example of a vision enhancing system is known as an enhanced vision system (hereinafter, “EVS”) and may be more generally described as being a sensor subsystem. Examples of enhanced vision systems are disclosed in U.S. Pat. Nos. 7,655,908 and 5,317,394. Additionally, an exemplary enhanced vision system is available for sale in the market place under product name EVS-II, manufactured by Kollsman, Inc. A typical EVS includes an imaging device, such as, but not limited to, a visible lowlight television camera, an infrared camera, or any other suitable light detection system capable of detecting light or electromagnetic radiation, either within or outside of the visible light spectrum. Such imaging devices are mounted to the aircraft and oriented to detect light transmissions originating from an area outside of the aircraft and are typically located ahead of the aircraft in the aircraft's flight path. The light received by the EVS is used by the EVS to form an image that is then displayed to the pilot on any suitable display in the cockpit of the aircraft. The sensor used in an EVS is more sensitive to light than is the human eye. Accordingly, using the EVS, a pilot can view elements of the topography that are not visible to the human eye. For this reason, an EVS is very helpful to a pilot when attempting to taxi or fly an aircraft in inclement weather or at night. One advantage to an EVS system is that it depicts what is actually present versus depicting what is recorded in a database.
Some display systems display both an SV image and an EV image display. For example, as a fused (merged) image (such as overlaying an EV image onto an SV image) or as a side-by-side display. The images may be indexed at the time of camera installation, e.g., by aligning an EV image sensor to ensure that the sensor and the SV view are indexed. Such a process may be periodically repeated during normal course of maintenance to assure proper alignment. Although such an overlaid “enhanced synthetic vision system” display may be useful, the display can be confusing, noisy, and difficult to interpret. For example, pixel averaging or alpha blending between SV and EV images can result with views being obscured with noisy or non-useful information, making it difficult for the pilot to interpret the information encoded on the display.
In addition to the above described vision systems, additional images, in the form of symbology, are typically presented to the pilot on the same display screen where the images from the EVS and the SVS are displayed. The symbology commonly appears as an icon or a series of icons on the display screen and may be indicative of, for example, the aircraft's heading, direction, attitude, orientation. Such symbology serves an important role in providing the pilot with situational awareness and controls concerning the orientation and attitude of the aircraft. This symbology is traditionally overlaid over the image presented by the SVS and the EVS.
However, the combination of the images from the EV and SV systems and the symbology provide a plethora of information for which the pilot's heads-up time and attention may be unnecessarily demanded.
These integrated symbology and EV and SV images are not necessarily suitable for all phases of flight operation. During the airborne phase, symbology must be prominently displayed for aircraft controls. During taxi operations after landing or prior to take off, pilots must pay more attention to the taxi environment. During low visibility conditions and night operations, the presence of EV images assist the pilot in readily identifying taxiways and objects ahead. However, typical flight symbology may interfere with an understanding of the displayed taxi environment EV images, and additional symbology elements may be needed to assist pilots in low visibility taxi environments.
Accordingly, it is desirable to provide an apparatus and method for improving the display of information necessary for taxi operations. Furthermore, other desirable features and characteristics of exemplary embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.